[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v9 1/6] x86: detect and initialize Cache QoS Monitoring feature
> -----Original Message----- > From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > Sent: Tuesday, March 18, 2014 6:09 PM > To: Xu, Dongxiao > Cc: andrew.cooper3@xxxxxxxxxx; Ian.Campbell@xxxxxxxxxx; > Ian.Jackson@xxxxxxxxxxxxx; stefano.stabellini@xxxxxxxxxxxxx; > xen-devel@xxxxxxxxxxxxx; konrad.wilk@xxxxxxxxxx; dgdegra@xxxxxxxxxxxxx; > keir@xxxxxxx > Subject: RE: [PATCH v9 1/6] x86: detect and initialize Cache QoS Monitoring > feature > > >>> On 18.03.14 at 11:02, "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx> wrote: > > Previously due to the large amount of data, we use the method to let Xen > > share the CQM pages to Dom0 in read only way to avoid data copy. > > However since the data amount is reduced a lot with above approach, do you > > think whether we still need to use this share way? Or like most of the other > > sysctl/domctl (e.g., xl list) command, which uses copy_to_guest() to pass > > the > > data? > > Iirc we're talking about a square table with each dimension being the > socket count. Considering an 8-node 4-socket system, that would > still be 1024 entries, i.e. exceeding a page in size. Hence I would > think that the read-only sharing approach might still be better. Of > course, if the data amount was smaller (and by so much that even > on huge systems it's no more than a page), that would be different. Okay. By using dynamic memory allocation and data sharing mechanism, we may need two hypercalls when Dom0 tool stack is querying CQM related info. - 1st hypercall is to let Xen allocate the memory and put CQM data there. - 2nd hypercall is to indicate Dom0 tool stack already digested the CQM data and Xen can free the memory. Does it sound reasonable to you? Thanks, Dongxiao > > Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |